qmeasure 1.2.6

Measurement code for condensed matter groups at UW based on QCoDeS.

MeasureIt

Measurement software based on QCoDeS, developed in University of Washington physics.

Start

To start, check examples/content/quick start.ipynb.

High-Level Design

MeasureIt is a measurement software package built on top of QCoDeS for physics experiments. The architecture follows these key patterns:

Core Architecture

• Sweep-based Measurement System: The core abstraction is the BaseSweep class with specialized implementations (Sweep0D, Sweep1D, Sweep2D) for different dimensional measurements
• Qt-based Threading: Uses PyQt5 with separate threads for data acquisition (RunnerThread) and plotting (PlotterThread)
• Driver Layer: Custom instrument drivers in the Drivers/ module that interface with various lab equipment
• Notebook Workflow: Designed for Jupyter/CLI usage; PyQt5 powers background threading and signaling
• Data Management: Integration with QCoDeS for data storage and experiment management

See related projects:

• AI enhancement: AI Integration
• WebUI: Qmeasure Jupyter (a small jupyterlab extension for generating sweeping code)

Key Components

• Base Classes: BaseSweep provides the foundation with parameter following, measurement creation, and thread management
• Measurement Types:
  • 0D (time-based measurements)
  • 1D (single parameter sweep)
  • 2D (dual parameter sweep)
• Queue System: SweepQueue for batch experiment execution
• Real-time Plotting: Live data visualization during measurements
• Station Management: QCoDeS Station integration for instrument management

Package Structure

src/measureit/
    sweep/             # Measurement implementations
    base_sweep.py      # Core sweep functionality
    tools/             # Data utilities and sweep helpers
    Drivers/           # Instrument drivers
    visualization/     # Plotting helpers

Quick Start

Prerequisites

• Python 3.11+
• NI DAQmx drivers: http://www.ni.com/en-us/support/downloads/drivers/download/unpackaged.ni-daqmx.291872.html
• NI VISA package: http://www.ni.com/download/ni-visa-18.5/7973/en/

Installation

Using pip (recommended)

pip install qmeasure

Note: The package is installed as qmeasure, but you import it as measureit:

import measureit  # Import name stays the same

From source

git clone https://github.com/nanophys/MeasureIt.git
cd MeasureIt
pip install -e .

Data Directory Configuration

MeasureIt (installed as qmeasure) stores databases, logs, and configuration files. You have three options:

Option 1: Use defaults

Data is automatically stored in OS-appropriate locations:

• Linux: ~/.local/share/measureit/
• macOS: ~/Library/Application Support/measureit/
• Windows: C:\Users\<username>\AppData\Local\measureit\

Option 2: Set environment variable (recommended)

export MEASUREIT_HOME="/path/to/your/data"  # Linux/macOS
set MEASUREIT_HOME="C:\path\to\data"        # Windows

Option 3: Programmatic configuration

import measureit
measureit.set_data_dir('/custom/path')

Updating MeasureIt (development version)

cd /path/to/MeasureIt
git pull
pip install -e . --upgrade

Known Issues

• ipykernel 7.0.x has a dormant event-loop bug that prevents the Qt/pyqtgraph plotter from updating. Stick to ipykernel>=6.29 (or the newer 7.1+ series).

Installation & Updating

It is useful to first create a conda environment to manage all the required packages for this package to work. First, download some form of conda (Miniforge3 is strongly recommended since it comes with mamba):

• Download Miniforge: https://github.com/conda-forge/miniforge
• Download Anaconda: https://www.anaconda.com/download/
• Download Miniconda: https://docs.conda.io/projects/miniconda/en/latest/miniconda-install.html

Basic Usage

Programmatic Usage

import measureit
from qcodes import Station

# Create a station and add instruments
station = Station()
# ... add your instruments ...

# Choose where databases should be stored (optional)
measureit.set_data_dir("/path/to/measureit-data")

# Create a 1D sweep
sweep = measureit.Sweep1D(
    set_param=dac.voltage,
    start=0,
    stop=1,
    step=0.01,
    inter_delay=0.1
)

# Follow parameters to measure
sweep.follow_param(dmm.voltage, lockin.x)

# Start the measurement
sweep.start()

Sweep Logging

• All sweeps and the SweepQueue now log status messages to timestamped files in the MeasureIt data directory's logs/ folder (see Data Directory Configuration above). Each run creates a file named sweeps_YYYYMMDD_HHMMSS.log that captures info/warning/error messages.

• To mirror those messages inside Jupyter notebooks, attach the notebook handler once per kernel:

  from measureit import attach_notebook_logging
  
  attach_notebook_logging()
  

  The handler safely marshals log output from background Qt threads back into the notebook cell output, so database switches and sweep transitions are visible while the queue runs.

Sweep Timing Constraints

MeasureIt enforces minimum delay values to ensure thread-safe operation and reliable measurement timing:

Parameter	Minimum Value	Applies To	Description
inter_delay	0.01s (10ms)	All sweeps (Sweep1D, Sweep2D inner)	Time between measurement points
outer_delay	0.1s (100ms)	Sweep2D outer sweep	Time between outer sweep lines

Why These Minimums?

• These minimums ensure reliable data collection and prevent measurement timing issues
• They protect the runner thread timing and ensure stable communication between measurement threads
• Values below these minimums will raise a ValueError with a descriptive error message
• The defaults (inter_delay=0.1s, outer_delay=1.0s) are safe for most use cases

Example:

# Valid sweep with minimum delays
sweep2d = measureit.Sweep2D(
    in_params=[inner_param, 0, 1, 0.01],
    out_params=[outer_param, 0, 10, 0.1],
    inter_delay=0.01,  # Minimum allowed
    outer_delay=0.1     # Minimum allowed
)

# This would raise ValueError: inter_delay too small
# sweep2d = measureit.Sweep2D(..., inter_delay=0.005)  # < 0.01s ❌

Documentation

Building Documentation

# Install documentation dependencies
uv pip install -e ".[docs]"  # or pip install -e ".[docs]"

# Build HTML documentation
cd docs/source
make html

The documentation is located in the docs/source directory. The built documentation will be in docs/source/_build/html/.

Online Documentation

Visit our online documentation for detailed guides and API reference.

Testing

MeasureIt includes a comprehensive test suite to ensure reliability and correctness.

Running Tests Locally

# Install development dependencies
pip install -e ".[dev,jupyter]"

# Run all tests
pytest

# Run with coverage report
pytest --cov=src/measureit --cov-report=html

# Run specific test categories
pytest tests/unit -v           # Unit tests only
pytest tests/integration -v    # Integration tests only
pytest -m "not slow"           # Skip slow tests

# Run tests with Qt debugging
export PYTEST_QT_API=pyqt5
export QT_LOGGING_RULES="*.debug=true"
pytest tests/integration -v -s

Test Organization

• tests/unit/: Fast, isolated unit tests for individual components
• tests/integration/: Tests for component interactions (Qt threads, signals)
• tests/e2e/: End-to-end tests for complete workflows
• tests/stress/: Performance and stress tests

Test Infrastructure

MeasureIt uses:

• pytest with pytest-qt for Qt event loop handling
• pytest-cov for coverage reporting
• Mock QCoDeS instruments for hardware-independent testing
• Temporary databases and isolated MEASUREIT_HOME per test
• The pytest-qt now creates so much trouble that we do not check it in CI on github workflows. But such a test can still be run locally to verify Qt-related functionality.

Continuous Integration

All unit tests run automatically on:

• Multiple Python versions (3.11-3.13)
• Multiple operating systems (Linux, Windows, macOS)
• Every push and pull request

Contributing

We welcome contributions! Please see CONTRIBUTING.md for detailed information about:

• Setting up a development environment
• Code quality standards and tools
• Testing guidelines
• Documentation standards
• Submitting pull requests

For quick development setup:

# Clone and set up development environment
git clone https://github.com/nanophys/MeasureIt
cd MeasureIt
uv pip install -e ".[dev,docs,jupyter]"  # or pip install -e ".[dev,docs,jupyter]"

# Run tests to verify setup
pytest tests/unit -v

External links and active known users

Seattle

David Cobden's lab

Xiaodong Xu's lab

Cambridge

Pablo Jarillo-Herrero's lab

Long Ju's lab